Solar energy world first in Australia

By Peter Hannam

Australian solar power researchers have achieved world-beating levels of efficiency, potentially making large solar plants more competitive with other energy sources such as coal.

A team from the Australian Centre for Advanced Photovoltaics (PV) at the University of NSW has achieved 40.4 per cent "conversion efficiency" by using commercially available solar cells combined with a mirror and filters that reduce wasted energy.

Pioneer: Professor Martin Green, director of the Australian Centre for Advanced Photovoltaics at the University of NSW.

Martin Green, the centre's director, said the independently verified breakthrough eclipsed previous records without resorting to special laboratory PV cells that "you've got no chance of buying commercially". Other top-performing solar panels convert about 36 per cent of the sunlight that falls on them into electricity.

The advance involved two steps. Three solar panels were stacked to capture energy from different wave lengths of sunlight, and then excess light from the stacked panels was directed by a mirror and filters to a fourth PV cell, making use of energy previously discarded.

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"This is our first re-emergence into the focused-sunlight area," said Professor Green, who pioneered 20 per cent-efficiency levels in similar technology in 1989.

The institute was prompted to revisit the technology in part because of Australian companies' efforts to develop large-scale solar towers using arrays of mirrors to focus sunlight on PV cells.

One of those firms, Melbourne-based RayGen, collaborated with UNSW on the project. It is building a plant in China with an solar conversion rate of about 28 per cent across the year.. "We'd take them to the mid-30s" for future projects with the technology jump, Professor Green said.

Professor Green was critical of the federal government's efforts to scrap the Australian Renewable Energy Agency – which chipped in $550,000 to the $1.3 million Power Cube project – and for its ongoing attempts to reduce the Renewable Energy Target set for 2020.

"A positive attitude to renewables would boost all these initiatives, a negative attitude will suppress them," he said. "Clamping down on deployment of renewables will make it more difficult for developments like this to see the light of day."

The next goal is to raise efficiency levels of concentrating solar to 42 per cent next year, about half way to the theoretical maximum level of 86 per cent. It's an issue likely to be discussed as Sydney plays host to the Asia-Pacific Solar Research Conference this week.

"It's horse and buggy days as far as solar is concerned at the moment. There's just this enormous potential for improvement in efficiency," Professor Green said.

"To turn your back on those types of developments doesn't seem to me to be a very sensible strategy."

It's horse and buggy days as far as solar is concerned at the moment.

Martin Green, director of the Australian Centre for Advanced Photovoltaics

The university's Mark Keevers led the engineering work on the so-called high efficiency spectrum splitting prototype, and its results were confirmed by the National Renewable Energy Laboratory (NREL) at its outdoor test facility in the US.